Laminated doctor



' May 5,1931. VEDD g 1,803,924

LAMINATED DOCTOR Filed April 2, 1928 JJ/zzz War-re)? We Ede Patented May5, 1931 UNITED STATES PATENT OFFICE JOHN WARREN VEDDER, OF WORCESTER,MASSACHUSETTS, ASSIGNOR TO RICE, BARTON & FALES, INCORPORATED, OFWORCESTER, MASSACHUSETTS,

MASSACHUSETTS A CORPORATION OF- LAMINATED DOCTOR Application filed April2, 1928. Serial No. 266,618.

This invention relates to doctors for calenders, dryers or other rolls.Its object is to provide a doctor of a flexible nature with meanswhereby the edge of the doctor blade in contact with the roll will besuiiiciently flexible longitudinally but not materially so transversely.

Reference is to be had to the accompanying drawing which is a transversesectional perspective view of a doctor showing a preferred form of thisinvention.

It is desirable to so construct the doctor blade in contact with theroll, that it will have sufiicient longitudinalflexibility to so conformits edge as to accommodate itself to any unevenness in the surface ofthe roll. However, flexibility in the transverse direction isundesirable. In a doctor which is flexibleboth longitudinally andtransversely,

pressure on the doctor causes the blade to turn u on an axis parallelwith the roll, and rovi es awedge shaped recess at the end of the bladewherein paper, grit, etc. tends to force itself and cause the doctor tobe ineffective. The grit will get into this wedgeshaped recess and scorethe roll, causing considerable damage. I

My invention comprises a flexible blade formed in laminated sections sothat its edge will be longitudinally flexible but will be prevented frombending transversely to such a degree as to permit said recess to beformed. 7

In the drawing I have shown the invention as applied to a rigid doctorback 10 which is ample ed in connection with the usual roll 11. T isdoctor back has a portion projecting toward the roll, preferably abovethe center thereof. On this back is mounted, by screws or the like 12,the doctor blade. This is made up of a series of flexible leaves 13 and14, each of which is adapted to engage the surface of the one below italong a line at a short distance from its edge. Thus the blade isbackedup to prevent its operative edge bending upwardly far enough to providea wedge shaped recess at its end where it touches the roll 11.

Although it will be seen that this blade is flexible, its flexibilityoperates only in the comparatively narrow space between the edge of theleaves 13 and the roll. It is free to yield beyond that edge but is helddown at a plurality of points at a distance from the doctor back andalong lines parallel with the roll and progressively farther away fromit.

In this way it will be seen that while the flexibility of the blade istaken advantage of to hold the blade against the roll and allow theblade to bend slightly all along its. edge to accommodate anyirregularities in the surface of the roll, it is held from any materialtransverse bending by its successive leaves.

This provides for the flexibility of the blade in a lengthwise directionand allows for the blade to accommodate itself perfectly to anyunevenness of the roll. At the same time it avoids material flexibilityin a transverse direction. The backing up of the blade by the upperleaves causes it to act practically as a rigid blade as far astransverse bending is concerned, although made of flexible material.

It will be noted that the blade '14, in the embodiment shown isunsupported from below except by the rigid member 10, the leaves 13 alloperating on the upper side of the blade 14.- It is to be understoodthat the terms upper and below are but relative and that if the roll- 11is reversed and the doctor accordingly turned about that sucharrangement is contemplated by the presentinvention. 85

Although I have illustrated and described only one form of theinventionI am aware of the fact that modifications can be made therein withoutdeparting from the scope of the invention as expressed in the claims.

Therefore I do not wish'to be limited in this respect but what I doclaim is 2-- 1. A doctor for the urposes described comprising a flexiblebla e mounted at a distance from its point of contact with the sur- 95face which it engages and made up of a series of flexible leaves, eachbearing on the one below alon a line at a short distance from the edge tereof and parallel therewith to prevent the blade from bendingf orgetting out 100 of position along that line and also prevent enoughtransverse flexibility to cause the hpper edge of the doctor to becomespaced ffrom the roll at any point. i 2. A doctor for the purposesdescribed, comprising two separate flexible leaves, a rigid support bywhich said leaves are carried, the lower leaf projecting beyond the edgeof the support and unsupported from below beyond said edge, the upperleaf projecting beyond said edge and its edge engaging the lower leafalong a line parallel to the operative edge of the lower leaf and saidedge of the support and at a material distance from both. i

3. A doctor for the purposes described, comprisin a flexible blade, arigid support having a ront edge parallel with the operative edge of theblade, said blade being se- 29 cured to said support, projecting beyondthe edge thereof, and unsupported from below beyond the edge of thesupport, and a series of entirely separate flexible leaves, all securedto the support at their rear edges and each projecting over the one nextbelow to a line part way between the line along which it is secured tothe support and the outer edge of the blade or leaf next below. w 4. Adoctor for the purposes described, 39 comprising a flexible blade, arigid support therefor beyond the edge of which the blade projects, anda spring leaf secured along one edge to said support and projecting overand engaging said blade along an area which 35 is unsupported directlyby said support, said leaf being free from the blade.

In testimony whereof I have hereunto affixed my signature.

40 JOHN WARREN VEDDER.

